1. Field of the Invention
The present invention relates to an image forming cartridge used in an electrophotographic printer, an electrophotographic copier and the like, and to an image forming apparatus.
2. Description of Related Art
A modern electrophotographic image forming apparatus generally forms an image in the following manner. First, the electrophotographic image forming apparatus exposes a surface of a photosensitive drum uniformly charged by a charging device with an exposure head, and thereby projects a desired image, character or the like onto the surface of the photosensitive drum to form an electrostatic latent image thereon. Then, the electrophotographic image forming apparatus develops the electrostatic latent image with toner in a triboelectrically charged image forming cartridge to form a toner image on the photosensitive drum, which serves as an image carrier, and thereafter transfers and fixes this toner image onto a medium.
In such an image forming apparatus, when a toner cartridge is replaced due to toner running low, a so-called fog noise is caused because new toner in the replaced new toner cartridge is not sufficiently charged. The fog noise is a phenomenon wherein toner particles attach to a portion that is not intended for developing. As a method for preventing this, Japanese Patent Application Publication No. 2002-258676 discloses a method of securing long times for triboelectrically charging toner in an image forming cartridge by incurring time to allow idling rotation of the image forming cartridge when a toner cartridge is replaced, for example.
However, in the above-described image forming apparatus of the related art, the extra time for idling rotation of the image forming cartridge is incurred every time and immediately after replacement of the toner cartridge. This prolongs stand-by time and subsequent print times.